arm64: Configure SCTLR_EL1 at boot
Some fields in SCTLR_EL1 are UNKNOWN at reset and the arm64 boot
requirements, as stated by Linux in Documentation/arm64/booting.rst, do not
specify a particular value for all the fields. Do not rely on the good will
of the hypervisor and userspace to set SCTLR_EL1 to a sane value (by their
definition of sane) and set SCTLR_EL1 explicitely before running setup().
This will ensure that all tests are performed with the hardware set up
identically, regardless of the KVM or VMM versions.
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
diff --git a/arm/cstart64.S b/arm/cstart64.S
index fcac9eb..62337a6 100644
--- a/arm/cstart64.S
+++ b/arm/cstart64.S
@@ -73,6 +73,12 @@
add x5, x5, :lo12:stacktop
sub x4, x5, #THREAD_SIZE
zero_range x4, x5
+
+ /* set SCTLR_EL1 to a known value */
+ ldr x4, =INIT_SCTLR_EL1_MMU_OFF
+ msr sctlr_el1, x4
+ isb
+
mov x4, #1
msr spsel, x4
adrp x4, stackptr
diff --git a/lib/arm64/asm/sysreg.h b/lib/arm64/asm/sysreg.h
index 9d6b4fc..18c4ed3 100644
--- a/lib/arm64/asm/sysreg.h
+++ b/lib/arm64/asm/sysreg.h
@@ -8,6 +8,8 @@
#ifndef _ASMARM64_SYSREG_H_
#define _ASMARM64_SYSREG_H_
+#include <linux/const.h>
+
#define sys_reg(op0, op1, crn, crm, op2) \
((((op0)&3)<<19)|((op1)<<16)|((crn)<<12)|((crm)<<8)|((op2)<<5))
@@ -87,4 +89,9 @@
#define SCTLR_EL1_A (1 << 1)
#define SCTLR_EL1_M (1 << 0)
+#define SCTLR_EL1_RES1 (_BITUL(7) | _BITUL(8) | _BITUL(11) | _BITUL(20) | \
+ _BITUL(22) | _BITUL(23) | _BITUL(28) | _BITUL(29))
+#define INIT_SCTLR_EL1_MMU_OFF \
+ SCTLR_EL1_RES1
+
#endif /* _ASMARM64_SYSREG_H_ */
